RF64W datasheet(51/76 Pages) HOPE

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ADVANCED COMMUNICATIONS & SENSING

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RF64

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Optional DC free data coding

CRC checksum calculation

Preamble

1 to 4 bytes

Sync W ord

1 to 4 bytes

Length

byte

Address

byte

Message

0 to (FIFO size - 1) bytes

CRC

2-bytes

Payload/FIFO

Fields added by the packet handler in Tx and processed and removed in Rx

Optional User provided fields which are part of the payload

Message part of the payload

Figure 44: Variable Length Packet Format

5.5.3. Tx Processing

In Tx mode the packet handler dynamically builds the packet by performing the following operations on the payload

available in the FIFO:

 Add a programmable number of preamble bytes

 Add a programmable Sync word

 Optionally calculating CRC over complete payload field (optional length byte + optional address byte +

message) and appending the 2 bytes checksum.

 Optional DC-free encoding of the data (Manchester or whitening).

Only the payload (including optional address and length fields) is to be provided by the user in the FIFO.

Assuming that the chip is already in Tx mode then, depending on IRQParam_Tx_start_irq_0 bit, packet

transmission (starting with programmed preamble) will start either after the first byte is written into the FIFO

(Tx_start_irq_0=1) or after the number of bytes written reaches the user defined threshold (Tx_start_irq_0=0). The

FIFO can also be fully or partially filled in Stby mode via PKTParam_Fifo_stby_access. In this case, the start

condition will only be checked when entering Tx mode.

At the end of the transmission (Tx_done = 1), the user must explicitly exit Tx mode if required. (e.g. back to Stby)

Note that while in Tx mode, before and after actual packet transmission (not enough bytes or Tx_done), additional

preamble bytes are automatically sent to the modulator. When the start condition is met, the current additional

preamble byte is completely sent before the transmission of the next packet (i.e. programmed preamble) is started.

5.5.4. Rx Processing

In Rx mode the packet handler extracts the user payload to the FIFO by performing the following operations:

 Receiving the preamble and stripping it off.

 Detecting the Sync word and stripping it off.

 Optional DC-free decoding of data.

 Optionally checking the address byte.

 Optionally checking CRC and reflecting the result on CRC_status bit and CRC_OK IRQ source.

Only the payload (including optional address and length fields) is made available in the FIFO.

Payload_ready and CRC_OK interrupts (the latter only if CRC is enabled) can be generated to indicate the end of

the packet reception.

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